diff --git a/python/mach/mach/test/python.ini b/python/mach/mach/test/python.ini
index fa00c644568d..c44b0acb89b0 100644
--- a/python/mach/mach/test/python.ini
+++ b/python/mach/mach/test/python.ini
@@ -4,7 +4,6 @@ subsuite = mach
 [test_conditions.py]
 skip-if = python == 3
 [test_config.py]
-skip-if = python == 3
 [test_dispatcher.py]
 [test_entry_point.py]
 [test_error_output.py]
diff --git a/python/mach/mach/test/test_config.py b/python/mach/mach/test/test_config.py
index 36d3c427b9d5..4d3778d6882a 100644
--- a/python/mach/mach/test/test_config.py
+++ b/python/mach/mach/test/test_config.py
@@ -140,7 +140,8 @@ class TestConfigSettings(unittest.TestCase):
         a = s.a
 
         # Assigning an undeclared setting raises.
-        with self.assertRaises(AttributeError):
+        exc_type = AttributeError if sys.version_info < (3, 0) else KeyError
+        with self.assertRaises(exc_type):
             a.undefined = True
 
         with self.assertRaises(KeyError):